The interrelationships among mental health care providers have become more complex and, in many respects, more competitive as a result of privatization and deinstitutionalization. The aim of this study is to identify and examine those local market and demographic characteristics that shape the competitive interactions of the three major types of mental health care providers: psychiatrists, community mental health agencies and hospitals. We will identify competitive strategies used by providers and link these behaviors to important outcomes: maintaining the accessibility to services, controlling costs of care and monitoring the nature of services provided. Previous research has focused primarily on characteristics of single types of providers. We will develop a predictive model of provider responses to local characteristics as they shape the delivery of care at two levels: the provider level and the community level. In this way we will be able to provide a backdrop for future research about whether various types of competition enhance or diminish the adequacy of mental health services. In order to study competitive interactions, we will develop operational measures of both within provider competition and inter-provider competition in markets (defined initially in terms of metropolitan statistical areas). The majority of the data for the study have already been collected in four national surveys conducted in 1988: the National Mental Health Facilities Study, the National Community Mental Health Center Study, The American -Psychiatric Association Biographical and Professional Activities Survey and the Inventory of Mental Health Organizations. These effects of competition have implications for the supply and distribution of public and private --- inpatient and outpatient---mental health services, especially for severely and chronically mentally ill patients with co-occurring disorders and children and adolescents.